This invention relates to magnetically operated lock structures. One magnetic lock structure is known from German Pat. No. 1,553,365. In this known construction, the locking members are magnetized so that the center line of the magnetic flux extends along a straight line. The outer ends of the locking means have a particular shape such that in a first unlocked position of the locking means the outer end of the locking member can move through a circular groove in the inner wall of the housing and in a second locked position the shape of the outer end of the locking member will prevent a turn of the outer end through the groove. The manufacture of said grooves extending in the circumferential direction along the inner surface of the external housing and of the locking members with the complicated outer ends is difficult and costly. At an attempt to force the lock the comparatively weak locking members are loaded by shearing forces. If in such an arrangement the locking members are close to one another, the magnetic locking can mutually affect one another so that, when the key is inserted, the locking members will not be turned into the correct position for unlocking the inner cylinder with respect to the external housing.
In order to solve these problems, the distance between the locking members has to be increased, but then only a limited number of locking members can be arranged in an inner cylinder of given length, so that the number of variations in the disposition of the co-operating key magnets and locking member magnets is considerably reduced.
In order to mitigate the disadvantage of this known construction the invention proposes to magnetize the rotatable locking member as well as the key magnet so that the magnetic flux passes through the interior of the key magnet and through the interior of the rotatable locking member along a curved line and extends beyond the key magnet and the rotatable locking member in a direction at least substantially parallel to the rotary axis of the locking member.
With this orientation of the magnetic flux the influence of a locking member on a neighboring locking member is materially lower than in the conventional arrangement so that the locking members can be disposed relatively near one another so that a lock of given length can accommodate a comparatively large number of locking members.
Surprisingly, the number of variations in the relative positions of the key magnets and the locking member magnets can be appreciably increased by a further effect achieved by the construction according to the invention. In a known lock having magnetic locking members, the key is provided with magnetic inserts having each a magnetic flux having a straight center line so that, when this center line is at right angles to the key and a North pole is located on one side of the key, the other side of the key will have a South pole. If the center line of the magnetic flux is parallel to the key, the positions of the North and South poles on both sides of the keys will be the same.
The locking members each have a rotational axis positioned in a plane which is substantially perpendicular to the axis of the inner cylinder. The locking members co-operate with a bolt rod extending in the direction of length of the inner cylinder, the disposition being such that, in the locked position, the bolt rod extends partly in a slot in the inner wall of the external housing and partly in the inner cylinder, while the locking members are arranged below the bolt rod and prevent a displacement of the bolt rod in the direction of the longitudinal axis of the inner cylinder, whereas in the non-locked position the locking members are turned so that the bolt rod is located opposite recesses in the locking members, in which recesses it can move in the direction of the longitudinal axis of the inner cylinder.
By using the construction according to the invention, the positions of the North and South poles on one side of the key may be chosen independently of the positions of the North and South poles on the other side of the key. It will thus be obvious that the number of variations in positions of key magnets and locking member magnets can be considerably raised when locking members are disposed on both sides of the key. In this regard, the construction according to the invention is also very suitable for use in a system having a mother key. The lock can be readily manufactured at low costs, since the slot in the wall of the inner housing extends in the direction of length of the housing and the tumbler members will have a simple shape.
In attempts to force the lock, the shearing load is absorbed by the solid bolt rod and the locking members are only loaded by pressure. The locking members can better withstand pressure load than shearing load.
A further advantage of the construction according to the invention is that it is not possible to determine in any way the accurate positions of the magnetic poles of the locking members so that the lock has a high safety against burglary.
Since the method of obtaining a magnetic flux having a curved center line is known, it is not necessary to include this method in the description of the construction according to the invention.